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A substantial proportion of Hong Kong's aging population suffers from osteoarthritis in both knees. Bilateral total knee arthroplasty (BTKA) is a surgical option for addressing this condition and can be performed via two approaches: simultaneous BTKA (SimBTKA) and staged BTKA (StaBTKA). We compared the cost-effectiveness and safety of these two methods in our institution. We retrospectively reviewed 2,372 patients (SimBTKA, 772; StaBTKA, 1,600; females, 1,780; males, 592; mean age at SimBTKA, 70.4 ± 7.99 years; mean age at StaBTKA, 66.4 ± 7.50 years; p  < 0.001) who underwent BTKA in our institution from 2001 to 2022. Patients were categorized according to the surgical approach. Patients undergoing BTKA in our institution were included. Particularly for SimBTKA, patients were assessed by anesthetists to be medically fit before undergoing the procedure according to their age, American Society of Anesthesiologists status, and osteoarthritis severity. The primary outcome was the length of stay (LOS) after surgery. The secondary outcomes were the 30-day unintended readmission, intensive care unit (ICU) admission, and death. SimBTKA had a shorter mean total LOS (acute hospital + rehabilitation center; SimBTKA, 13.09 days; StaBTKA, 18.12 days; p  < 0.001) and mean LOS in acute hospital (SimBTKA, 7.70 days; StaBTKA, 10.42 days; p  < 0.001). However, no significant difference was found in the mean LOS in rehabilitation centers (SimBTKA, 5.47 days; StaBTKA, 6.32 days; p  > 0.05) between the two approaches. The 30-day unintended readmission rate was lower in SimBTKA (SimBTKA, 2.07%; StaBTKA, 3.30%; odds ratio [OR] = 1.60; p  > 0.05) but statistically insignificant. SimBTKA was less costly than StaBTKA by US$ 8,422.22 per patient. No significant differences in ICU admission and death rates were found ( p  > 0.05) between the two groups. SimBTKA had a shorter LOS and lower cost than StaBTKA and comparable complication rates. Therefore, SimBTKA should be indicated in medically stable patients., Competing Interests: None declared., (Thieme. All rights reserved.)

Anticipating implant sizes before total knee arthroplasty (TKA) allows the surgical team to streamline operations and prepare for potential difficulties. This study aims to determine the correlation and derive a regression model for predicting TKA sizes using patient-specific demographics without using radiographs. We reviewed the demographics, including hand and foot sizes, of 1,339 primary TKAs. To allow for comparison across different TKA designs, we converted the femur and tibia sizes into their anteroposterior (AP) and mediolateral (ML) dimensions. Stepwise multivariate regressions were performed to analyze the data. Regarding the femur component, the patient's foot, gender, height, hand circumference, body mass index, and age was the significant demographic factors in the regression analysis (R-square 0.541, p  < 0.05). For the tibia component, the significant factors in the regression analysis were the patient's foot size, gender, height, hand circumference, and age (R-square 0.608, p  < 0.05). The patient's foot size had the highest correlation coefficient for both femur (0.670) and tibia (0.697) implant sizes ( p  < 0.05). We accurately predicted the femur component size exactly, within one and two sizes in 49.5, 94.2, and 99.9% of cases, respectively. Regarding the tibia, the prediction was exact, within one and two sizes in 53.0, 96.0, and 100% of cases, respectively. The regression model, utilizing patient-specific characteristics, such as foot size and hand circumference, accurately predicted TKA femur and tibia sizes within one component size. This provides a more efficient alternative for preoperative planning., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  The use and the optimal timing of tourniquet during primary total knee arthroplasty (TKA) is controversial. Most previous studies failed to show clinically significant differences in different strategies. The aim of this study was to determine how three strategies of tourniquet application affect the outcome in TKA patients., Methods:  This was a prospective randomized controlled study. Patients who undergo TKA were randomized into one of the three groups (1:1:1 ratio): tourniquet inflated from skin incision to cement hardening, tourniquet from cement application to hardening, and tourniquet from skin incision to skin closure. The perioperative blood loss, limb swelling, and complications were recorded. The level of hemoglobin, hematocrit, C-reactive protein (CRP), interleukin (IL)-6, creatine kinase (CK), and lactate dehydrogenase (LDH) were determined. Patients' thigh and TKA wound pain, Knee Society knee score (KSKS) and Knee Society functional assessment (KSFA) scores, and rehabilitation parameters were evaluated., Results:  A total of 90 patients were enrolled. The baseline characteristics were comparable. We only found significant difference in the intraoperative blood loss (skin to cement: 58.7 ± 36.1 mL, cement-only: 147.8 ± 107.9 mL, skin to skin: 16.3 ± 13.1 mL, p  < 0.0001). There were no statistical differences in postoperative drainage, thigh/knee circumference, change of hemoglobin/hematocrit, CRP, IL-6, CK, and LDH on day 1 to day 4 after surgery. The thigh/TKA wound Visual Analogue Scale scores, KSKS score, KSFA score, and rehabilitation parameters were not significantly different at up to 6-month follow-up. No thromboembolic events were noted., Conclusion:  Our results revealed that there was no best tourniquet strategy in TKA. Different tourniquet methods can be utilized based on surgeon preference without affecting outcomes., Competing Interests: None declared., (Thieme. All rights reserved.)

Although local infiltration analgesia (LIA) is effective in relieving pain after total knee arthroplasty (TKA), its effect is short lasting and the optimal combination of drugs is unknown. Steroids being a potent and long-acting anti-inflammatory drug might extend LIA's effect. This study aims to evaluate the role of steroids in LIA. This is a paired-randomized controlled study involving one-stage bilateral TKA patients. LIA containing ropivacaine, ketorolac, and adrenaline with or without triamcinolone was given. One knee was randomized to receive LIA with steroids, while the other received LIA without steroids. The primary outcome was knee pain in terms of the visual analog scale (VAS). Secondary outcomes were rehabilitation progress, functional scores, and complications. Outcomes were compared between the knees of the same patient and documented up to 1 year. A total of 45 patients (90 TKAs) were included. LIA with steroid knees showed lower VAS score at rest and during activity from postoperation day 1 to 5 and at 6 weeks ( p  < 0.05). Passive and active range of movement was also greater in LIA with steroid group from day 1 to 7 and day 2 to 5, respectively ( p  < 0.05). Steroid-treated knees also achieved active straight leg raise earlier (1.2 vs. 2.0 days, p  < 0.05). No differences in Knee Society Score and complication rates between both groups. Steroids in LIA offer additional and extended benefit in pain control and rehabilitation after TKA, while no adverse effects were found up to 1-year follow-up., Competing Interests: None declared., (Thieme. All rights reserved.)

Background: Postoperative pain remains a major barrier to a patient's recovery after total knee arthroplasty (TKA). Periarticular corticosteroids in local infiltration analgesics (LIA) and high-dose intravenous corticosteroids have individually shown to improve pain control after TKA. However, potential interactions between them have not been investigated. This study aims to evaluate any combination effect of both routes of corticosteroids in TKA., Methods: This is a double-blinded, paired, randomized controlled trial involving 1-stage bilateral TKAs. All received 16 mg of dexamethasone intravenously. One knee was randomized to receive LIA with 40 mg of triamcinolone, while the other knee receives LIA without corticosteroids. For each patient, one knee was affected by intravenous steroids only, while the other was under the combined effect of intravenous and periarticular steroids (IVPAS). Knee pain, Southampton wound scores, and functional knee scores (Knee Society Knee Score and Oxford Knee Scores) were compared between knees of the same patient., Results: Forty-six patients (92 TKAs) were included. IVPAS knees showed significantly lower visual analog scale scores from day 1 to 6 weeks (P < .05) and a larger range of movement from day 2 to 4 (P < .05). IVPAS knees achieved active straight leg raise earlier than intravenous steroids (1.6 vs 2.3 days, P < .05). No differences in Southampton wound scores and functional knee scores for up to 1 year., Conclusion: Combining intravenous and periarticular corticosteroids improved pain control and recovery after TKA with no increase in wound complications up to 1 year., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Corticosteroids can reduce pain but the optimal dose and safety profiles are still uncertain., Objective: This study aimed to evaluate two different doses of dexamethasone for pain management and their side effects after total knee arthroplasty., Design: A prospective randomised, controlled trial., Setting: A tertiary teaching hospital in Hong Kong., Patients: One hundred and forty-six patients were randomly allocated to one of three study groups., Interventions: Before operation, patients in group D8, D16 and P received dexamethasone 8 mg, dexamethasone 16 mg and placebo (0.9% saline), respectively., Main Outcome Measures: The primary outcome was postoperative pain score. Secondary outcomes were opioid consumption, physical parameters of the knees and side effects of dexamethasone., Results: Compared with placebo, group D16 patients had significantly less pain during maximal active flexion on postoperative day 3 [-1.3 (95% CI, -2.2 to -0.31), P = 0.005]. There was also a significant dose-dependent trend between pain scores and dexamethasone dose (P = 0.002). Compared with placebo, patients in group D16 consumed significantly less opioid [-6.4 mg (95% CI, -11.6 to -1.2), P = 0.025] and had stronger quadriceps power on the first three postoperative days (all P < 0.05). They also had significantly longer walking distance on postoperative day 1 [7.8 m ([95% CI, 0.85 to 14.7), P = 0.023] with less assistance during walking on the first two postoperative days (all P < 0.029) and significantly better quality-of-recovery scores on postoperative day 1 (P = 0.018). There were significant dose-dependent trends between all the above parameters and dexamethasone dose (all P < 0.05). No significant differences were found in the incidence of chronic pain or knee function 3, 6 and 12 months postoperatively., Conclusion: Dexamethasone 16 mg given before total knee arthroplasty led to a reduction in postoperative pain, less opioid consumption, stronger quadriceps muscle power, better mobilisation and better overall quality-of-recovery after operation. No long-term improvement in reduction in pain and function of the knee was found., Trial Registration: ClinicalTrials.gov identifier: NCT02767882.

Understanding the anatomy and biomechanics of the medial collateral ligament (MCL) is crucial in producing good outcomes after total knee arthroplasty. A solid grasp of the surgical techniques that address the MCL are necessary to ensure good coronal plane ligament balance. Furthermore, intraoperative injury to the MCL in total knee arthroplasty is an uncommon yet serious complication which often goes unrecognized. Loss of the integrity of the MCL can lead to instability, loosening, and accelerated polyethylene wear. There is still controversy regarding the ideal method of treatment of intraoperative MCL injuries with suggested treatment modalities ranging from conservative management to use of varus-valgus constrained implants.

Introduction: Osteoarthritis (OA) of the knee is a growing problem in an aging population. Unicompartmental knee arthroplasties (UKA) have been used for management of isolated OA of the medial tibiofemoral joint. This is the first study on the usage of UKA in Hong Kong., Methods: Retrospective analysis of all patients undergoing medial compartment UKA in a tertiary referral center since 2003. Preoperative and postoperative International Knee Society Knee Scores (KSKS) and Knee Societal Functional Assessment (KSFA) scores, range of motion, flexion deformity, and lower limb mechanical alignment were measured. Statistical analysis using paired sample t-tests was performed. Revision operations, rate of revisions, and causes of failure were analyzed. Univariate and multivariate logistic regression analyses of risk factors for revision operation were performed against patient demographics, type of prosthesis, postoperative alignment, and degree of correction., Results: There were 94 UKA performed with an average follow-up of 4.3 years (range: 0.5-15.2 years). The KSKS and KSFA scores improved from 54.5 and 54.0 to 85.6 and 64.5 ( p < 0.01), respectively. There was no significant improvement in the range of motion ( p = 0.87) and fixed flexion deformity ( p = 0.14). Mechanical alignment improved from 172.1° to 174.9° varus postoperatively ( p < 0.01). Six cases required revision operation with a revision rate of 1.50 per 100 observed component years. Causes of revision included two cases of tibial tray loosening and one case each of progressive OA, mechanical failure, persistent pain, and infection. Logistic regression analysis for risk factors showed no statistical significance., Conclusions: UKA offers good functional improvement but further long-term studies are required to evaluate survivorship.

Background: Wound closure is key to prevent infection, facilitate immediate rehabilitation, and improve efficiency of total knee arthroplasty (TKA). Continuous knotless suturing with barbed suture can potentially save time and distribute tension more evenly. However, its role in TKA in terms of cost-effectiveness and wound complications is not clear. This study aims at comparing barbed and traditional sutures' wound closure time and cost in primary TKA., Methods: One hundred nine knees were randomized into either barbed or traditional group. Synthetic absorbable sutures (Vicryl, Ethicon Inc) and bidirectional barbed sutures (Stratafix, Ethicon Inc) were used. Arthrotomy and subcutaneous wound closure time, wound complications, and rehabilitation parameters in terms of range of motion and Knee Society Score were compared. Patients were followed up to 3 months., Results: Traditional sutures had significantly more positive leak tests (10 vs 2, P value <.05) and wound complications (11 vs 2, P value <.05). No differences in range of motion and Knee Society Score were noted. Arthrotomy and subcutaneous closure time were significantly shorter with barbed sutures (arthrotomy 325 seconds vs 491 seconds; subcutaneous 306 seconds vs 381 seconds, P value <.05). Concerning cost of suture material and operation time, barbed suture on average saved USD 48.7 per TKA in our local institute., Conclusion: Bidirectional barbed suture improves the cost-effectiveness of TKA through reducing wound closure time and wound complications., (Copyright © 2016 Elsevier Inc. All rights reserved.)

This study aims to report our experience of managing acute periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) with surgical debridement and prostheses retention. A review of patients in our prospective joint replacement register from 1998 to 2013 was performed. In this study, 34 patients with 35 TKAs were included; 25 were infections after primary TKA and 10 were after revision TKA. For primary TKA infections, after a mean follow-up of 53.8 ± 42.6 months, 11 were successfully treated, while 14 failed, including 10 required reoperations and 4 needed lifelong antibiotic suppression. The success rate of debridement was 44.0%. Statistical analyses showed no significant differences between the two groups on patients' age, time lag between symptoms onset and debridement, preoperative C-reactive protein, erythrocyte sedimentation rate, white blood cell count, hemoglobin, albumin, glucose, or synovial fluid total cell count. Patients' primary diagnoses or staphylococcal infections had no significant impact on the surgical outcomes either. Debridement with polyethylene insert exchange had significantly higher success rate than debridement alone, with all 13 cases without exchange failed. All 10 cases with infections after revision TKA had failed. We concluded that debridement with prostheses retention has a low success rate for acute PJI following primary TKA. The polyethylene insert should be exchanged during surgery. For acute infections after revision TKA, total revision should be contemplated., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Purpose: The current study investigated the accuracy in achieving proper lower limb alignment and individual component positions after total knee arthroplasty (TKA) with 3 different instrumentation techniques. It was hypothesized that patient-specific instruments (PSI) would achieve more accurate lower limb alignment and component positions compared to conventional instruments (CON)., Methods: Ninety knees in 81 patients were randomized in 1:1:1 ratio into CON, computer navigation (NAV) and PSI groups to receive TKA. The surgical routines were standardized. The lower limb mechanical axis and individual component positions were assessed on standard radiographs. Tourniquet time, operation time and patients' functional scores were documented., Results: Conventional instruments and PSI were more likely to result in an excessively flexed femoral component (p = 0.001) compared to NAV. Number of outliers in postoperative lower limb alignment, and other components positions in the coronal and sagittal plane showed no statistically significant difference. The mean tourniquet time and operation time was significantly shorter in CON and PSI groups than NAV group (p < 0.001). Four early complications occurred in the PSI group (p = 0.015). At 3-month follow-up, there was no difference in terms of the knee range of motion and patients' function among the 3 groups., Conclusion: No significant radiological and clinical benefit could be demonstrated in using PSI over CON or NAV in TKA. Routine use of PSI is not recommended because of the extra cost and waiting time., Level of Evidence: I.

Purpose: Femoral sizing in total knee replacement is important. Either undersizing or oversizing may result in deleterious effects to the clinical outcome after the surgery. There has been no study on the precision and accuracy of femoral sizing and the effect of measurement at different landmarks over the distal femur. This study assesses the intra-observer and inter-observer error of femoral sizing and identifies the effect of the placement site of the anterior referencing tool on femoral sizing., Methods: Five investigators with different clinical experience measured the femoral size of 10 cadaveric specimens twice using three anterior referencing tool. The measurement of the femoral size was repeated at nine designated points on the anterior cortex of the cadaveric femora., Results: Excellent intraobserver and interobserver agreements were obtained using the three anterior referencing tools. When the size on which the majority agreed was regarded as the actual size of the specimen, measurement at the nine designated points on the anterior cortex showed a deviation from the actual size from 6.2 to 46.2 %. Placing the femoral sizer stylus at the middle and 2 cm above the proximal margin of the anterior femoral condyle yielded the highest precision and accuracy., Conclusion: Regardless of the experience of the surgeons, measurement of the femoral size using the three anterior referencing tools is very accurate. Placing the stylus of the femoral sizer at the middle and 2 cm above the proximal margin of the anterior femoral condyle best reflects the actual size of the femur., Level of Evidence: Experimental study.

This study compares the efficacy of pain control using continuous femoral nerve block (FNB) and multimodal periarticular soft tissue injection. This is a randomized, crossover, clinical trial. Sixteen patients having bilateral osteoarthritis of the knee scheduled for staged total knee arthroplasty were randomized to receive either FNB (0.2% ropivacaine), via indwelling catheter for 72 hours, or multimodal periarticular soft tissue injection in the first stage. In the second stage, they received the opposite treatment. The primary outcome measure was morphine consumption by patient-controlled analgesia in the first 72 hours postoperatively. Cumulative morphine consumption as well as rest pain and motion pain in the first 72 hours was comparable between the 2 groups. The functional outcomes did not differ significantly. We conclude that multimodal periarticular soft tissue injection provides comparable analgesia to continuous FNB after total knee arthroplasty., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Purpose: To compare total knee arthroplasty (TKA) patients who received continuous femoral nerve block (FNB) with local anaesthetics through a catheter versus patient-controlled analgesia (PCA) with intravenous morphine., Methods: 50 women and 10 men aged 51 to 84 years with matched characteristics underwent TKA and received either continuous FNB with local anaesthetics through a catheter (n=30) or PCA with intravenous morphine (n=30). None of the patients had had previous knee surgery. All operations were performed according to the standard protocol. Daily mean pain numerical rating scale at rest (NRS-R) and during movement (NRS-M), requirement of extra pain control, complications related to pain control, and overall patient satisfaction in both groups were compared., Results: Both groups were similar in terms of pain NRS-R and NRS-M, overall satisfaction, and length of hospital stay. Within each group, pain NRS-M score was significantly higher than pain NRS-R score. In the FNB group, 3 patients had dislodgement of the femoral catheter on day 1 and switched to PCA with intravenous morphine. Two of them had fair satisfaction. Patients in the PCA group had significantly more side-effects (nausea, vomiting, dizziness, and pruritis); 2 of the 5 patients with nausea and vomiting had fair satisfaction. No patients had any surgical complication., Conclusion: Both FNC and PCA provide reliable pain control.

Bone deficiency hinders implant alignment and stabilisation of the bone-implant interface in revision total knee arthroplasty (TKA). Treatments for bone defects include bone cement, bone cement with screw reinforcement, metal augments, impaction bone grafts, structural allografts, and tantalum, depending on the location and size of the defects. Small defects are usually treated with cement, cement plus screws, or impaction allograft bone. Large defects are repaired with structural allografts or metal augments. Recent developments involve the use of highly porous osteoconductive tantalum. We reviewed the pros and cons of each method for bone defect management in revision TKA.

There are several classification systems for bone defects in revision total knee arthroplasty. Each has its own drawbacks, and none satisfies all the clinical demands. Therefore, a new classification system and treatment guideline based on a combination of criteria (location, side, containment, and severity of the bone defect) is necessary.

Anterior dislocation of a posterior stabilised total knee arthroplasty secondary to a polyethylene tibial post fracture is rare. We report one such case in an 89-year-old Chinese woman who had undergone total knee arthroplasty using the Insall Burstein II prosthesis 7 years earlier. The failure was due to sagittal malalignment of the components. Owing to more pronounced anterior bowing of the distal femoral shaft in southern Chinese, neutral component placement is often biased toward hyperextension. When the knee reaches full extension, anterior impingement occurs. Surgeons must therefore take extra care in preoperative planning and bone cutting in this population.

Two hundred thirty-six posterior stabilized total knee arthroplasties (TKAs) were performed consecutively. Twenty-seven patellar clunk syndromes were identified in 25 patients. Insall-Salvati ratio, position of joint line, postoperative patellar height, and anterior-posterior position of tibial tray were measured. It was found that postoperative low-lying patella (P<.001) and anterior placement of tibial tray (P=.011) was associated with patellar clunk syndrome. Thirteen patients had bilateral TKAs of the same prosthesis (5 bilateral AMK knees and 8 bilateral Insall Burstein knees) but unilateral patellar clunk syndrome. The nonclunk sides were used as control for comparison with the clunk sides. The congruency and tilting of the patellar button in the skyline view were documented. It was observed that the congruency of the patellar button was less satisfactory in the clunk side (P=.019).